The purpose of this study was to verify the effectiveness of an internal family systems therapy program aimed at increasing ego-identity of middle-aged women. The objectives of this program were for middle-aged women to differentiate the self of internal systems, to identify constraints impinging on an individual part, to release constraints impinging on an individual part, to harmonize the internal family, and to enhance ego-identity. 31 middle-aged women ranged in age from 40 to 60. Two groups were identified as equivalents for the study in the pre-test. The program of this experimental group was implemented twice a week for 120 minutes per each session over a 6-week period. The pre-test(Aug. 29. 2006), the post-test(Oct. 20. 2006) and the follow-up test(Nov. 20. 2006) were implemented in order to verify the effectiveness of the programs. The participants who were absent more than three times in the program were excluded from the post-test and follow-up test. Eventually, the data in 31 persons(15 for the internal family systems therapy, 16 for the control group) were analyze to verify the effectiveness of the program. The instruments used in the study were the ego-identity scale. The data were analyzed using repeated measures ANOVA, simple main effect, post-hoc t-test, means and standard deviations. And the program was from Sep. 5. to Oct. 20. 2006. The findings of the study were as follows: The internal family systems therapy program had significant effects on enhancing the ego-identity. There was a large increase of the ego-identity in the intervention group, compared with control group at post treatment and follow-up after 1 month which indicated the continuity of intervention effect. However, in the control group, there were no changes according to the time.